Field of the Disclosure
The disclosure relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which a digitizer is detachable.
Discussion of the Related Art
Liquid crystal display (LCD) devices are most widely used for monitors of notebook computers, monitors of personal computers and televisions due to low power consumption, thin thickness and large screen. LCD devices use the optical anisotropy and polarization properties of liquid crystal molecules of a liquid crystal layer to produce an image.
An LCD device includes two substrates spaced apart from and facing each other and a liquid crystal layer interposed between the two substrates. The alignment direction of the liquid crystal molecules is controlled by varying the intensity of an electric field applied to the liquid crystal layer, and the transmittance of light through the liquid crystal layer is changed.
The LCD devices require an additional light source because the LCD devices are not self-luminescent. Therefore, a backlight unit is disposed at a rear side of a liquid crystal (LC) panel and emits light into the LC panel, whereby discernible images can be displayed.
Backlight units are in general classified as edge type or direct type according to the position of a light source with respect to a display panel. In an edge-type backlight unit, a light source is disposed at one side or at each of two sides of a light guide plate of a backlight unit and light from the light source is reflected by the light guide plate or a reflection plate to be provided to the display panel. In a direct-type backlight unit, a plurality of light sources such as lamps is disposed directly under the display panel. The direct-type backlight unit has been widely used for LCD devices having a large screen of more than 20 inches because it does not require a light guide plate, has high utilization rate of light, is simply handled, and is not limited in a screen size.
The LC panel and the backlight unit are modularized with various mechanical components to be protected from outer impacts and to prevent light loss.
Meanwhile, a digitizer may be used as an input device of an LCD device. The digitizer recognizes (X,Y) coordinate of a display device and detects a specific content or key value.
Accordingly, a user can easily input desired values using an electromagnetic pen or probe.
Hereinafter, an LCD device including a digitizer as an input device according to the related art will be described with reference to FIG. 1.
FIG. 1 is a cross-sectional view of illustrating an LCD device according to the related art.
In FIG. 1, the related art LCD device includes a cover bottom 28, a backlight unit 30, a liquid crystal panel 10, a digitizer 40, a guide panel 13, and a case top 15. The digitizer 40 is disposed between the backlight unit 30 and the liquid crystal panel 10.
The cover bottom 28 encloses the liquid crystal panel 10 and the guide panel 13.
The backlight unit 30 provides light to the liquid crystal panel 10 and includes a light guide plate 24, a reflection sheet 26, optical sheets 22 and a lamp assembly 27. The lamp assembly 27 includes a lamp housing 27a and LED lamps 27b. 
In the meantime, liquid crystal cells are arranged in an active matrix form between upper and lower substrates of the liquid crystal panel 10. Transmittance of the liquid crystal cells is changed according to a video signal, and an image corresponding to the video signal is displayed.
A printed circuit board 11 is connected to the lower substrate of the liquid crystal panel 10 along at least an edge of the lower substrate via a connecting means 12. The printed circuit board 11 may be bent toward a side surface of the guide panel 13 or a rear surface of the cover bottom 28.
The case top 15 encloses sides and edges of the liquid crystal panel 10, the guide panel 13 and the cover bottom 28 and is combined with the cover bottom 28 to form a liquid crystal module.
In the liquid crystal module, since the printed circuit board 11 is bent toward the side surface of the guide panel 13 or the rear surface of the cover bottom 28, a bezel are of the LCD device may be decreased.
In the meantime, the digitizer 40 includes a sensor which detects the location indicated by the electromagnetic pen or probe.
At this time, the digitizer 40 detects external electromagnetic changes. Since electromagnetic fields penetrate the liquid crystal panel 10, digitizer 40 is able to recognize movements of the electromagnetic pen over the liquid crystal panel 10 even if the digitizer 40 is disposed under the liquid crystal panel 10.
By the way, when the digitizer 40 is installed at a rear surface of the liquid crystal module, the digitizer 40 may malfunction because the digitizer 40 is affected by interference of electromagnetic waves generated from the printed circuit board 11.
However, the digitizer 40 is installed to the liquid crystal module, and the LCD device is released. Since the manufacturer needs to buy the digitizer 40, to install the digitizer 40 to the liquid crystal module, and to release the LCD device including the digitizer 40, the manufacturing costs increase. On the other hand, there is a problem that the user cannot decide whether or not the digitizer 40 is installed.